The purpose of this study was to find out whether people flying long-haul developed clots in the leg. Before this paper was published deep vein thrombosis (DVT) had been mentioned in a few case reports. We thought that flying might cause clots, some of which could be very serious. We used colour duplex ultrasound imaging to to detect very small clots. We found these in 12 out of 100 passengers flying long-haul. All these clots were small and in most passengers dissolved without treatment. In the remaining passengers anti-coagulants were given and the clots all dissolved before they became important. What this study has shown is that it is extremely common to develop small clots. We still do not know how many passengers will go on to get a bigger clot, either affecting the leg on a long-term basis, or travelling to the lung. At the same time we studied these passengers, a further 100 passengers were fitted with Medi-travel elastic stockings. These stockings squeezed the leg, promoting blood flow through the deep veins and preventing the deeper veins from enlarging during long periods of sitting. We were unable to detect any clots in the deep veins in these 100 passengers. The use of the Medi-travel elastic stockings prevents the development of DVT.

Four of the passengers wearing elastic stockings complained of pain in the surface veins. These passengers had large varicose veins. They had developed superficial thrombophlebitis – clots in surface veins. Passengers with bad varicose veins are prone to the stocking rubbing on the veins and causing inflammation. Superficial thrombophlebitis is not a serious condition although it can be quite painful.

In summary, passengers who fly long-haul are at risk of developing small clots in the leg veins. Some passengers will go on to develop bigger clots and more serious problems. The use of an elastic compression stocking (Medi-travel) is an effective way of reducing this risk.

Recommendations – Preventing Deep Vein Thrombosis:

This study has proven the link between air travel and the development of deep vein thrombosis. We make the following recommendations: Any passenger with a history of clots or co-existing medical problems such as heart trouble, lung trouble, cancer or a recent operation should consult their own general practitioner before travelling. Your general practitioner can assess whether there is a real risk and advise you appropriately.

For Passengers in Good Health, We Would Make the Following Recommendations:

Before travelling obtain a pair of Medi-travel elastic stockings (mediuk.co.uk). These should be worn for the duration of the flight, both outbound and inbound. Before getting on the aeroplane take a reasonable amount of exercise and avoid drinking alcohol.

When on the aeroplane drink plenty of water and avoid excessive consumption of alcohol. Whilst you are sitting in your seat, move your feet up and down regularly and if you can get out of your seat, walk round the aeroplane. If you are not walking round your aeroplane and you are in your seat with your seatbelt fastened, moving the feet up and down does promote the flow of blood through the legs.

We believe these simple measures are effective in reducing the risk of developing even a small blood clot. This will prevent a large blood clot from developing.